This invention relates to communications circuitry, and more particularly, to serial communications circuitry used in conveying signals over circuit interconnects.
Integrated circuits contain various regions of circuitry. Metal lines called interconnects are used to convey signals between these different circuit regions.
It has recently become apparent that conventional circuit designs cannot simply be scaled up in size indefinitely. For example, microprocessor designers have begun to explore multi-core architectures as an alternative to constructing ever-larger microprocessor chips. Particularly in designs such as these, large numbers of signals need to be conveyed from one portion of an integrated circuit to another.
Large numbers of signals also need to be conveyed between blocks of circuitry on integrated circuits such as programmable logic device integrated circuits. In modern programmable logic device integrated circuit, circuit blocks no longer all perform identical functions. Memory blocks are used for data storage, digital signal processing blocks are used for specialized data processing functions, and programmable logic blocks are used for user logic. The broad range of functions that are implemented in the circuit blocks can place a burden on the interconnect infrastructure. Modern programmable logic device integrated circuits also tend to have circuit blocks that are larger and more complex than older devices, which further burdens the interconnects.
In a typical programmable logic device, rows and columns of interconnects are selectively coupled to each other using programmable switches at row and column intersections. Because of the custom nature of programmable logic device integrated circuits, programmable logic device integrated circuits may need to have several times as many interconnects as comparable custom logic circuits. Programmable logic device integrated circuits may therefore be particularly sensitive to interconnect inefficiencies.
One way to ensure that a given programmable logic device integrated circuit has sufficient interconnect resources to implement a desired circuit design is to over-provision the interconnect fabric. By providing many interconnects, logic designers are ensured that their designs can be implemented without exhausting available interconnect resources. However, as the number of interconnects that are included on an integrated circuit increases, the size of the integrated circuit increases. This, in turn, makes the distances between circuit blocks on the integrated circuit larger and creates new interconnect challenges.
There is therefore a need for improved integrated circuit interconnect structures.